Industries which utilize large quantities of paint, such as the automobile industry, typically purchase paint from the paint manufacturers in large tanks which are commonly referred to as "totes". The tank contains therein a substantial quantity of the liquid or suspension, such as paint, to facilitate handling and transporting from the paint manufacturer to the user. The tank normally has a blade-type mixer or agitator positioned internally thereof and attached to a mixing shaft which projects through the top wall of the tank. When the tank arrives at the user location, and when use of the contents is desired, the user attaches a drive unit to the projecting end of the mixing shaft so as to permit mixing of the contents.
In one known arrangement of this type which has been marketed for several years, as sold by Mixing Equipment Co., the drive unit, which is maintained in the user's possession so that only the tanks need to be transported between the paint manufacturer and the user, is attachable to or detachable from the tank so that the drive unit can be readily used for mixing the contents of a large number of tanks. In this known drive unit, however, the attachment to or detachment from the tank is structurally and operationally more complex than desired. For example, the drive unit possesses a coupling arrangement for attachment to the tank which includes two bayonet-type couplings, namely one for attaching the drive housing to the tank, and another for attaching the driving shaft to the mixing shaft. Since a bayonet coupling itself requires a combination of relative axial and rotary movements, the fact that this drive unit requires two such bayonet couplings hence makes attachment and detachment of the drive unit relative to the tank a more complex operation than desired.
Further, in the above arrangement, after the drive housing-tank coupling has been engaged, the operator must then physically grasp and manually lift the mixing shaft upwardly to engage it with the drive coupling followed by relative rotation to lock the shaft to the drive coupling. Such can be a difficult and strenuous manipulation.
Thus, this invention relates to a drive unit having a quick-connect drive coupling associated therewith so that a common drive unit can be readily attached to or detached from a tank which carries its own mixing shaft, whereby the drive unit can be easily and efficiently coupled to or detached from a plurality of such tanks with minimal effort and time, and without requiring manual upward lifting of the mixing shaft. Further, this improved drive unit and specifically the improved quick-connect drive coupling is believed to be of increased structural and operational simplicity.